宜昌香溪河大桥4号桥塔墩钢围堰设计与施工  

Design and Construction of Steel Cofferdam for No.4 Pylon Pier of Xiangxi River Bridge in Yichang

作　　者：陈开桥 CHEN Kai-qiao(China Railway Major Bridge Engineering Group Co. , Ltd. , Wuhan 430050, China)

机构地区：[1]中国中铁大桥局集团有限公司

出　　处：《世界桥梁》2019年第4期22-26,共5页World Bridges

摘　　要：宜昌香溪河大桥主桥为主跨470m的双塔双索面混合梁斜拉桥。桥址位于三峡库区,为解决库区深水大落差基础施工难题,4号桥塔墩基础施工采用先平台后围堰施工方案。钢围堰为圆形双壁钢套箱围堰,外直径为33.2m,内直径为30.2m,高35.3m。围堰竖向分4节,横向分24块,在工厂制作好后运至现场安装。对围堰侧板和封底混凝土的承载力进行了验算,结果满足规范要求。钢围堰安装前,对主跨侧河床进行回填,边跨侧河床进行清理。为避免库区高水位落差影响,在桩基施工期间同步安装底节围堰。为确保围堰主跨侧河床顺利抛填,在底节围堰主跨侧安装钢挡板。围堰和钢挡板用片石或砂包堵漏,清理刃脚、钢护筒周围泥土,保证封底混凝土和钢结构的粘结力。The main bridge of Xiangxi River Bridge in Yichang is a two-pylon hybrid girder cable-stayed bridge with a main span of 470 m. The stay cables are fanned out in double cable planes. The bridge site is located at the Three Gorges Reservoir Region, where the great water depth and large water depth differences pose tremendous challenges to the foundation construction. For the construction of No.4 pylon pier foundation, an integral scheme was designed, in which the construction platform was installed first, and then the cofferdam was launched and sunk into position. The steel cofferdam is the round double-walled steel box cofferdam, with an external diameter of 33.2 m, an inner diameter of 30.2 m, and a height of 35.3 m. The cofferdam was vertically divided into 4 lifts, and transversely into 24 blocks for fabrication in the factory, and then delivered to the bridge site for installation. The load bearing capacities of cofferdam side walls and base seal concrete were checked and the results met the code requirements. The riverbed on the main span side was backfilled, and the riverbed on the side-span side was cleared before the steel cofferdam installation. To avoid the influence of high water level difference in the reservoir region, the base lift of the cofferdam was installed in parallel to the construction of the pile foundation. To ensure that the riverbed on the main span side could be backfilled smoothly, steel stopping plates were added to the base lift of the cofferdam facing the main span. The ripraps and sand bags were brought to plug the cofferdam for leakage and the steel stopping plates, and soil around the cutting edges and steel casings was cleared, to ensure the binding force between the base seal concrete and the steel structure.

关 键 词：斜拉桥 桥塔墩 圆形双壁钢套箱围堰 结构设计 河床清理 钢挡板 抛填堵漏 施工技术 

分 类 号：U448.27[建筑科学—桥梁与隧道工程] U443.162[交通运输工程—道路与铁道工程]